Shoe Sole Focusing on Windlass Mechanism

ABSTRACT

The second transverse groove, provided in an area between the Chopart&#39;s joint and the Lisfranc joint, including the navicular bone where the arch of the foot is highest, is deeper than the first transverse groove, and is equal to or deeper than the third transverse groove. Therefore, the rest of the midsole is thin and it becomes easier for the shoe sole to flex, thereby facilitating the upward displacement of the area where the arch is highest. Thus, it is possible to suppress the lowering of the arch even if an exercise is continued over a long time. On the other hand, a flexion area including at least one third transverse groove is provided directly below the talus, and has a larger width than other transverse grooves. This makes it easier for the rear foot portion directly below the talus to flex, thereby facilitating the upward displacement of the area of the arch.

TECHNICAL FIELD

The present invention relates to a shoe sole focusing on the windlassmechanism.

BACKGROUND ART

Shoes with multiple or many transverse grooves extending in thetransverse direction on the bottom surface of the shoe sole are wellknown in the art.

CITATION LIST Patent Literature

First Patent Document: U.S. Pat. No. 7,168,190 B1 (front page)

Second Patent Document: US2011-016746 A1 (front page)

Third Patent Document: US2011-232130 A1 (front page)

Fourth Patent Document: PCT/US2004/033111 (abstract)

Fifth Patent Document: JP07-289306 A (abstract)

SUMMARY OF INVENTION

However, these conventional techniques are probably not focusing on thewindlass mechanism and using this mechanism.

Now, it is known that when the MP joint is hyperextended, the plantaraponeurosis is tensioned to thereby pull the calcaneal bone forward,thus increasing the arch height, and this series of actions is calledthe “windlass mechanism”.

It is known that the arch being raised by the windlass mechanism enablesan efficient transmission of the kick force when kicking off the groundwhile walking or running. On the other hand, lowering of the arch maylead to flatfoot and hallux valgus.

With recent shoes of which the middle foot portion is hardened withresin parts, the middle foot portion of the sole does not easily deform,and the foot movement is restricted. Thus, the deformation of the archof the foot tends to be small. Therefore, even if the toe portion has aneasy-to-flex structure, the arch portion of the sole does not flex so asto protrude upward.

On the other hand, shoes of which the sole easily deforms are also soldin recent years, but with these shoes, the arch portion of the sole islikely to drop, causing the arch of the foot to lower. Therefore, withthese shoes, the arch is unlikely to rise. That is, no shoes have beendeveloped, which likely take advantage of the windlass mechanism whilerunning.

It is therefore an object of the present invention to provide astructure of a shoe sole with which it is possible to raise and maintainthe arch height by utilizing the windlass mechanism.

A shoe sole of the present invention includes:

-   -   an outsole having a tread surface and placed at least in a fore        foot portion and a rear foot portion; and    -   a midsole placed above the outsole and placed in the fore foot        portion, a middle foot portion and the rear foot portion,        wherein:    -   the outsole and/or the midsole define:        -   a first transverse groove continuously extending in a            transverse direction from a medial edge so as to reach at            least a longitudinal axis of a foot at a position of a            metatarsal phalangeal joint and/or a base of a proximal            phalanx of first to third toes;        -   at least one second transverse groove continuously extending            in the transverse direction from the medial edge so as to            reach at least the longitudinal axis, in an area between a            Chop art's joint of the first toe to a posterior end of a            Lisfranc joint; and        -   at least one third transverse groove continuously extending            in the transverse direction from the medial edge so as to            reach at least the longitudinal axis, in an area between an            anterior end to a posterior end of a talus, wherein:    -   the second and third transverse grooves are provided so as to be        depressed upwardly from a bottom surface of the shoe sole;    -   each of the grooves has a front wall surface and a rear wall        surface opposing the front wall surface, which the front and        rear wall surfaces define each of the grooves;    -   an average value of a width of a flexion area is larger than an        average groove width of the first transverse groove and is        larger than an average groove width of each of the at least one        second transverse groove, wherein the flexion area is an area        extending from a most anterior one of the front wall surfaces of        the at least one third transverse groove to a most posterior one        of the rear wall surfaces of the at least one third transverse        groove; and    -   an average depth of the at least one second transverse groove is        larger than an average depth of the first transverse groove and        is equal to or larger than an average depth of each of the at        least one third transverse groove.

According to the present invention, the presence of the secondtransverse groove and the third transverse groove allows for a portionof the shoe sole from the middle foot portion to the rear foot portionto deform (flex) into an upwardly protruding shape. Therefore, when thetoe is elevated facing upward and the MP joint is extended over thefirst transverse groove, the plantar muscles, including at least theplantar aponeurosis, are rolled up upward, thereby tensioning theplantar aponeurosis, which makes it easier for the arch of the foot torise.

Particularly, the second transverse groove, provided in an area betweenthe Chopart's joint and the Lisfranc joint, including the navicular bonewhere the arch of the foot is highest, is deeper than the firsttransverse groove, and is equal to or deeper than the third transversegroove. Therefore, the rest of the midsole is thin and it becomes easierfor the shoe sole to flex, thereby facilitating the upward displacementof the area where the arch is highest.

That is, if no reinforcement device is provided in the middle footportion, the midsole in the middle foot portion tends to be thick alongthe arch of the foot. Therefore, with the second transverse groovehaving a large depth, the shoe sole is easily flexed over the secondtransverse groove even if the midsole overall has a large averagethickness.

Therefore, it is possible to suppress the lowering of the arch even ifan exercise is continued over a long time.

On the other hand, a flexion area including at least one thirdtransverse groove is provided directly below the talus, and has a largerwidth than other transverse grooves. This makes it easier for the rearfoot portion directly below the talus to flex, thereby facilitating theupward displacement of the area of the arch.

Note that the groove width of the second transverse groove is smallerthan the width of the flexion area, thereby making it possible tosuppress the lowering of the arch. Moreover, the flexion area has alarge width and thus easily undergoes compressive deformation, whichmakes it possible to absorb the impact on the heel.

The term “flexion area” as used in the present invention means thatwhere there are a plurality of third transverse grooves, the grooveratio is 30% or more and less than 100%, wherein the groove ratio is thetotal value of the groove widths of the plurality of third transversegrooves with respect to the distance from the most anterior one of thefront wall surfaces of the plurality of third transverse grooves, whichare directly below the talus, to the most posterior one of the rear wallsurfaces of the plurality of third transverse grooves. This is because asufficient ease of flexing cannot be obtained if it is less than 30%.Note that for a similar reason, the groove ratio is preferably 40% ormore, and most preferably 50% or more.

The “longitudinal axis of the foot” as used in the present invention isrepresented by a straight line that connects between the center of theheel and the midpoint between the center of the ball of the big toe andthe center of ball of the little toe.

The term “to extend in the transverse direction” does not only mean toextend in the exact transverse direction that is perpendicular to thelongitudinal axis, but also include a diagonally slant direction and ameandering shape.

The phrase “the first transverse groove extends in the transversedirection at the position of the MP joint (metatarsal phalangeal joint)or the base of the proximal phalanx of the first to third toes” meansthat at least a portion of the first transverse groove is provided so asto overlap with a portion of the MP joint or the base of the proximalphalanx of the first to third toes.

The term “groove width” as used in the present invention means the widthof a groove at the lower end thereof where an opening is formed.Therefore, the average groove width means the average value of the widthof the groove at the lower end thereof where an opening is formed. Notethat the term “average groove width” means that the width of the firstor second transverse groove may locally be larger than the width of theflexion area.

The groove width of each groove is preferably about 1 mm to 50 mm.

The reason for the groove width of each groove to be 1 mm or more is forallowing the shoe sole to flex into an upwardly protruding shape in themiddle foot portion. Note that the groove width exceeding 50 mm willhinder the stability of the foot support.

Note that the term “average depth” means that the first or thirdtransverse groove may locally be deeper than the second transversegroove. Where the groove has a V-letter shape or a U-letter shape, theaverage depth means the value obtained by averaging the largest depthsalong the cross section parallel to the longitudinal axis. That is, itmeans the average depth for the area where V-shaped or U-shapeddepressions are connected together.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic medial side view showing a shoe for the left footaccording to Embodiment 1 of the present invention.

FIG. 2 is a schematic lateral side view showing a shoe for the rightfoot according to Embodiment 1 of the present invention.

FIG. 3 is a schematic bottom view showing the same.

FIG. 4 is a schematic medial side view showing the shoe with its shoesole being flexed.

FIG. 5 is a schematic bottom view showing a shoe sole of Embodiment 2.

FIG. 6 is a schematic medial side view showing a shoe according toEmbodiment 3 of the present invention.

FIG. 7 is a schematic medial side view showing a shoe according toEmbodiment 4 of the present invention.

FIG. 8 is a schematic medial side view showing a shoe according toEmbodiment 5 of the present invention.

FIG. 9 is a schematic medial side view showing a shoe sole according toEmbodiment 6 of the present invention.

FIG. 10 is a schematic bottom view showing a shoe sole of Embodiment 7.

FIG. 11 is a schematic cross-sectional view showing a shoe according toEmbodiment 8 of the present invention.

FIG. 12 is a schematic cross-sectional view showing the shoe with itsshoe sole being flexed.

FIG. 13 is a plan view showing the foot bone structure. FIGS. 14A, 14Band 14C are graphs showing test results for Test Example 1, Test Example2 and Reference Example, respectively.

DESCRIPTION OF EMBODIMENTS

Preferably, an average groove width of at least one of the thirdtransverse groove is larger than the average groove width of the firsttransverse groove and is larger than the average groove width of each ofthe at least one second transverse groove.

In this case, the flexing capability of the rear foot portion willfurther improve.

More preferably, the shoe sole further includes an auxiliary transversegroove continuously extending in the transverse direction from themedial edge so as to reach at least the longitudinal axis at a positiondirectly below a base or a shaft of a first metatarsal bone.

In this case, with the auxiliary transverse groove being placed slightlyanterior to the deepest second transverse groove, the shoe sole willlikely flex smoothly in conformity with the shape of the arch whose apexis at the navicular bone.

Note that the shaft refers to a portion between the base and the head,and the thickness thereof typically changes smoothly. The base refers toa portion of each bone that is close to the posterior (heel side) jointand that is slightly expanding to a greater thickness, and it isreferred to also as the proximal head. On the other hand, the headrefers to a portion of each bone that is close to the anterior (toeside) joint and that is slightly expanding to a greater thickness, andit is referred to also as the distal head.

More preferably, an average depth of the auxiliary transverse groove issmaller than the average depth of the second transverse groove, and anaverage groove width of the auxiliary transverse groove is smaller thanthe average groove width of at least one of the third transverse groove.

The auxiliary transverse groove having a small depth and a small widthwill further smoothen the flexion of the shoe sole in conformity withthe shape of the arch whose apex is at the navicular bone, and will notassist in lowering the arch of the foot.

Preferably, the first transverse groove is depressed upwardly from thetread surface.

This makes it easier for the MP joint to be extended over the firsttransverse groove.

In this case, more preferably, each of the grooves is defined by thefront wall surface, the rear wall surface and a ceiling above;

-   -   a thickness from an upper surface of the midsole to the ceiling        of the first transverse groove is set to be 0.5 mm or more and        10 mm or less and less than 12 mm at a thinnest portion;    -   a thickness from the upper surface of the midsole to the ceiling        of the second transverse groove is set to be 0.5 mm or more and        10 mm or less at a thinnest portion; and    -   a thickness from the upper surface of the midsole to the ceiling        of the third transverse groove is set to be 0.5 mm or more and        10 mm or less at a thinnest portion.

In this case, the midsole flexes at the thinnest portion. Therefore, ifthe thickness of the first transverse groove to the ceiling is over 12mm at the thinnest portion or if the thickness of the second and thirdtransverse grooves to the ceiling is over 10 mm at the thinnest portion,the midsole will not easily flex.

If the thinnest portion is less than 0.5 mm, it will be difficult tomanufacture the midsole.

Preferably, a maximum depth of the second and third transverse groovesis 5 mm or more and 40 mm or less;

-   -   the maximum depth of each of the at least one second transverse        groove is larger than a thickness of a portion of the midsole        that is directly above an area where the second transverse        groove having that maximum depth is provided; and    -   the maximum depth of each of the at least one third transverse        groove is larger than a thickness of a portion of the midsole        that is directly above an area where the third transverse groove        having that maximum depth is provided.

In this case, as the second and third transverse grooves are deep, athin portion is formed in the middle foot portion of the midsole,thereby allowing for the shoe sole to flex in the middle foot portion.

Preferably, the average depths of the second and third transversegrooves are 5 mm or more and 40 mm or less;

-   -   the average depth of at least one, preferably two or more, of        the second transverse groove is larger than an average thickness        of a portion of the midsole that is directly above an area where        the at least one second transverse groove is provided; and    -   the average depth of at least one of the third transverse groove        is larger than an average thickness of a portion of the midsole        that is directly above an area where the at least one third        transverse groove is provided.

In this case, as the second and third transverse grooves are deep andthe midsole is thin, it is even easier for the shoe sole to flex in themiddle foot portion.

Note that if the maximum depth or the average depth is less than 5 mm,the shoe sole will not easily flex. On the other hand, if these valuesare over 40 mm, the shoe sole will be too thick.

Preferably, the second transverse groove continuously extends across theshoe sole from the medial edge to a lateral edge of the foot; and

-   -   the second transverse groove has a larger average depth on a        medial side of the foot than an average depth thereof on a        lateral side of the foot.

The arch of the foot is higher on the medial side than on the lateralside. Therefore, as the average depth of the second transverse groove islarger on the medial side than on the lateral side, the shoe sole caneasily flex following the rise of the arch of the foot.

Preferably, the third transverse groove continuously extends across theshoe sole from the medial edge to a lateral edge of the foot; and

-   -   the third transverse groove has a larger average depth on a        medial side of the foot than an average depth thereof on a        lateral side of the foot.

The arch of the foot is higher on the medial side than on the lateralside. Therefore, as the average depth of the third transverse groove islarger on the medial side than on the lateral side, the shoe sole caneasily flex following the rise of the arch of the foot.

Preferably, there are a plurality of second transverse grooves, and theaverage depth of at least two second transverse grooves is larger thanthe average depth of the first transverse groove and is equal to orlarger than the average depth of each of the at least one thirdtransverse, groove.

In this case, the middle foot portion can easily flex smoothly.

Preferably, there are a plurality of third transverse grooves, and anaverage groove width of at least two of the third transverse grooves islarger than the average groove width of the first transverse groove andis larger than the average groove width of each of the at least onesecond transverse groove.

In this case, the posterior end of the middle foot portion can easilyflex smoothly in conformity with the posterior portion of the arch ofthe foot.

Preferably, the shoe sole is further provided with a longitudinal grooveextending from the first transverse groove to the third transversegroove; and

-   -   the shoe sole further comprises a band portion placed in the        longitudinal groove, the band portion extending from the fore        foot portion, which is anterior to the first transverse groove,        to the rear foot portion, which is posterior to the third        transverse groove, the band portion being secured to the shoe        sole in the fore foot portion and in the rear foot portion, and        the band portion being formed by a material that is less        stretchable than the midsole and the outsole.

In this case, when the toes are elevated, a similar load to that on theplantar aponeurosis is applied on the band portion, and then the shoesole flexes because the band is less stretchable. Thus, the arch islikely to rise when the toes are elevated.

More preferably, an abrasion-resistant material, which is lesssusceptible to abrasion than the band portion, is attached to a lowersurface of the band portion, and the band portion and theabrasion-resistant material together form the band.

In this case, the band can be placed close to the tread surface.

More preferably, a bottom surface of the band is placed above the treadsurface.

Where there are projecting objects such as stones on the road surface,as the band lands on such a projecting object, a flexing force mayinadvertently be applied to the shoe sole. As the bottom surface of theband is afloat, it is possible to suppress such an inadvertent flexion.

EMBODIMENTS

The present invention will be understood more clearly from the followingdescription of preferred embodiments taken in conjunction with theaccompanying drawings. Note however that the embodiments and thedrawings are merely illustrative and should not be taken to define thescope of the present invention. The scope of the present invention shallbe defined only by the appended claims. In the accompanying drawings,like reference numerals denote like components throughout the pluralityof figures.

Embodiments of the present invention will now be described withreference to the drawings.

FIGS. 1 to 4 show Embodiment 1. Note that in order to facilitate thedescription of the invention, FIG. 1 shows the medial side of a shoe forthe left foot whereas FIG. 2 shows a lateral side view of a shoe for theright foot.

As shown in FIGS. 1 and 2, a shoe sole includes an outsole 1, and amidsole 2. In various figures, minute grooves (so-called a design)formed on a tread surface 1S of the outsole 1 are omitted.

In the present embodiment, the outsole 1 and the midsole 2 are placedacross the fore foot portion F, the middle foot portion M and the rearfoot portion R. The outsole 1 is formed by a foamed or non-foamedrubber, for example, and has the tread surface 1 s which has a higherabrasion resistance than the midsole 2 and which is to be in contactwith the road surface.

The midsole 2 is formed by a foamed resin such as EVA, for example, andis placed on the outsole 1, as shown in FIG. 2, for reducing the impactof landing. Therefore, the midsole 2 is formed thicker than the outsole1.

The hardness of the midsole 2 is preferably 45 to 75 degrees and morepreferably 50 to 70 degrees in JIS C hardness, for example.

In the present embodiment, a first transverse groove G1, secondtransverse grooves G2, third transverse grooves G3, and auxiliarytransverse grooves G4 are formed both in the outsole 1 and in themidsole 2. As shown in FIG. 3, each of the transverse grooves G1 to G4extends from a medial edge 10 to a lateral edge 11 in a directionperpendicular to the longitudinal axis A1 or in a slant directioncrossing the longitudinal axis A1.

Note that as is clearly shown in FIG. 13, the longitudinal axis A1 isplaced along a straight line that connects between the midpoint O3(between the ball O1 of the big toe and the ball O5 of the little toe)and the center O4 of the heel.

In FIG. 1, the first transverse groove G1 continuously extends in thetransverse direction X from the medial edge 10 to the lateral edge 11(FIG. 3) at the position of the metatarsal phalangeal joint MP and/orthe base B30 of the proximal phalanx B3 of the first to third toes. Thefirst transverse groove G1 makes it easier for the metatarsal phalangealjoint MP to flex.

The second transverse grooves G2 continuously extend in the transversedirection X from the medial edge 10 to the lateral edge 11 (FIG. 3), inan area between the Chopart's joint JS of the first toe and theposterior end JLb of the Lisfranc joint JL. In the present embodiment,there are two (a plurality of) second transverse grooves G2, and the twosecond transverse grooves G2 work in cooperation with each other,thereby forming the middle foot flexion area MA.

Note that NB denotes the navicular bone, and CB denotes the medialcuneiform bone.

The third transverse grooves G3 continuously extend in the transversedirection X from the medial edge 10 to the lateral edge 11 (FIG. 3), inan area between the anterior end Tf and the posterior end Tb of thetalus Ta. In the present embodiment, there are two (a plurality of)third transverse grooves G3, and the two third transverse grooves G3work in cooperation with each other, thereby forming the rear footflexion area BA.

The auxiliary transverse grooves G4 continuously extend in thetransverse direction X from the medial edge 10 to the lateral edge 11(FIG. 3) at a position directly below the base B40 or the shaft B41 ofthe first metatarsal bone B4.

In the present embodiment, there are two (a plurality of) auxiliarytransverse grooves G4, and the two auxiliary transverse grooves G4 workin cooperation with each other, thereby forming an auxiliary flexionarea SA.

The first to fourth transverse grooves G1 to G4 are provided so as to bedepressed upwardly from the bottom surface of the shoe sole, i.e., thetread surface 1 s in the present embodiment. Note that the firsttransverse groove G1 may be formed so as to be depressed downwardly fromthe upper surface of the midsole 2.

Each of the grooves G1 to G4 includes a front wall surface Fw, a rearwall surface Bw opposing the front wall surface Fw, and a ceiling T0,which define the groove G1 to G4.

In the present embodiment, the middle foot flexion area MA is defined asan area extending from the most anterior one of the front wall surfacesFw of the plurality of second transverse grooves G2 to the mostposterior one of the rear wall surfaces Bw of the plurality of secondtransverse grooves G2. The average value of the width D20 of the middlefoot flexion area MA is larger than the average groove width D1 of thefirst transverse groove 1.

Note that the average value of the width D20 of the middle foot flexionarea MA may be less than or equal to the average distance from theanterior end Tf to the posterior end Tb of the talus Ta.

The rear foot flexion area BA is defined as an area extending from themost anterior one of the front wall surfaces Fw of the plurality ofthird transverse grooves G3 to the most posterior one of the rear wallsurfaces Bw of the plurality of third transverse grooves G3. The averagevalue of the width Da of the rear foot flexion area BA is larger thanthe average groove width D1 of the first transverse groove G1, and islarger than the average groove width D20 of the middle foot flexion areaMA.

In the present embodiment, the average groove width D3 of each of thethird transverse grooves G3 is larger than the average groove width D1of the first transverse groove G1, and is larger than the average groovewidth D2 of each of the second transverse grooves G2.

In order to expect that windlass will raise the foot arch, the soles 1and 2 need to flex and deform so as to protrude upward in the middlefoot portion M. Then, the groove widths of the second to fourthtransverse grooves G2 to G4 may possibly decrease. There are alsomanufacturing-related problems. Therefore, the average groove width ofeach of the first to fourth transverse grooves G1 to G4 would need to beat least about 1 mm.

On the other hand, the maximum value of the average groove width of eachof the first to fourth transverse grooves G1 to G4 would be 50 mm. Ifthe value exceeds 50 mm, the sole itself, which supports the sole of thefoot, drops down, thereby leading to lowering of the arch.

In view of the above, the range of the average groove width for each ofthe first to fourth transverse grooves G1 to G4 is preferably 2 mm to 40mm and most preferably about 3 mm to 30 mm.

As can be seen from a comparison between FIG. 1 and FIG. 2, the secondto fourth transverse grooves G2 to G4 become shallower from the medialedge 10 toward the lateral edge 11.

Therefore, the second transverse groove G2 has a larger average depth onthe medial side of the foot than that on the lateral side of the foot.Similarly, the third transverse groove G3 has a larger average depth onthe medial side of the foot than that on the lateral side of the foot.Similarly, the fourth transverse groove G4 has a larger average depth onthe medial side of the foot than that on the lateral side of the foot.

In FIG. 2, the average depth H2 of each of the second transverse groovesG2 is larger than the average depth H1 of the first transverse grooveG1, and is equal to or larger than the average depth H3 of each of thethird transverse grooves G3.

On the other hand, the average depth H4 of the auxiliary transversegroove G4 is smaller than the average depth H2 of the second transversegroove G2, and the average groove width D4 of the auxiliary transversegroove G4 is smaller than the average groove width D3 of the thirdtransverse groove G3.

The average depths H2 and H3 of the second and third transverse groovesG2 and G3 are set to be about 5 mm to 40 mm. If the average depths H2and H3 are smaller than 5 mm, the effect of this mechanism cannot be soexpected, whereas if they are larger than 40 mm, the sole will be toothick. In view of this, the above value is preferably 7 mm to 35 mm, andmost preferably 10 mm to 30 mm.

The average depth 112 of at least one of the second transverse groovesG2 is larger than the average thickness T2 a of a portion of the midsole2 that is directly above an area where the transverse groove isprovided. On the other hand, the average depth H3 of at least one of thethird transverse grooves G3 is larger than the average thickness T3 a ofa portion of the midsole 2 that is directly above an area where thetransverse groove is provided.

For similar reasons to those for the average depth, the maximum depth Hmof the second and third transverse grooves G2 and G3 of FIG. 1 ispreferably about 5 mm to 40 mm, more preferably about 7 mm to 35 mm, andmost preferably about 10 mm to 30 mm.

The average depth 112 of each of the two second transverse grooves G2 islarger than the average depth H1 of the first transverse groove G1, andis equal to or larger than the average depth H3 of each of the thirdtransverse grooves G3.

In FIG. 1, the maximum depth Hm of each of the second transverse groovesG2 is larger than the thickness of a portion of the midsole 2 that isdirectly above an area where the transverse groove having that maximumdepth is provided. On the other hand, the maximum depth Hm of each ofthe third transverse grooves G3 is larger than the thickness of aportion of the midsole 2 that is directly above an area where thetransverse groove having that maximum depth is provided.

As shown in FIG. 1, the thickness T1 from the upper surface of themidsole 2 to the ceiling T0 of the first transverse groove G1 is set tobe 0.5 mm or more and less than 12 mm at the thinnest portion.

On the other hand, the thickness T2 from the upper surface of themidsole 2 to the ceiling T0 of the second transverse groove G2 is set tobe 0.5 mm or more and 10 mm or less at the thinnest portion.

The thickness T3 from the upper surface of the midsole 2 to the ceilingT0 of the third transverse groove G3 is set to be 0.5 mm or more and 10mm or less at the thinnest portion.

The average groove width D3 of each of the two third transverse groovesG3 is larger than the average groove width D1 of the first transversegroove G1 and is larger than the average groove width D2 of each of thesecond transverse grooves G2.

Next, the deformation of the shoe in the present embodiment will bedescribed briefly.

When the fore foot portion F of FIG. 1 faces up as indicated by a solidline with respect to a virtual line of FIG. 4, and the MP joint MP isextended over the first transverse groove G1, the plantar aponeurosis isrolled up upward, thereby tensioning the plantar aponeurosis, whichurges the arch of the foot to rise. During this movement, the lowerportion of the sole shrinks in the longitudinal direction Y over thearea of the second to fourth transverse grooves G2 to G4, and theoutsole 1 and the midsole 2 deform into an upwardly protruding shape.Thus, the arch of the foot is likely to be raised during this movement.

Next, other examples of the present invention will be described.

In other examples to be described below, like elements to those ofEmbodiment 1 will be denoted by like reference numerals, and only thosestructures that are different from Embodiment 1 will be described.

As shown in Embodiment 2 of FIG. 5, some or all of the second to fourthtransverse grooves G2 to G4 may be set to a length such that they extendfrom the medial edge 10 toward the lateral edge 11 past the longitudinalaxis A1 but do not reach the lateral edge 11. The arch of the foot ishigh on the medial side, and the effect of the windlass mechanism can betherefore expected as long as the medial side portion of the sole canflex sufficiently.

Preferably, the transverse grooves G1 to G4 can extend over about ⅔ thetotal width from the medial edge 10 to the lateral edge 11 in the areawhere the transverse grooves G1 to G4 are provided.

Note that as opposed to the example shown in FIG. 5, the second andthird transverse grooves G2 and G3 may be provided across the totalwidth, whereas the first and fourth transverse grooves G1 and G4 areprovided so as to extend from the medial edge 10 past the longitudinalaxis A1 and into a part of the lateral side portion.

As with the first transverse groove G1 shown in FIG. 5, the transversegrooves G1 to G4 do not need to be extending in a directionperpendicular to the longitudinal axis A1, but may be extending in aslant direction crossing the longitudinal axis A1.

In Embodiment 3 of FIG. 6, there may be a single, i.e., only one, secondtransverse groove G2 that is deeper than the third transverse groove G3.In this example, the depth of a second transverse groove G2 that isimmediately anterior to the posterior second transverse groove G2 issmaller than the depth of one of the third transverse grooves G3.

Where there is one second transverse groove G2 that is deeper than thethird transverse groove G3, as in this example, at least the ceiling TOof the second transverse groove G2 is preferably placed directly belowthe navicular bone NB. This is because the navicular bone NB is locatedat the apex of the arch of the foot.

In Embodiment 4 of FIG. 7, there is only one each of the firsttransverse groove G1, the second transverse groove G2 and the thirdtransverse groove G3. In this case, the width Da of the third transversegroove G3 is generally equal to the rear foot flexion area BA.

As shown in Embodiments 5 and 6 of FIGS. 8 and 9, the width D2 of thesecond transverse groove G2 may be larger than the width D3 of any ofall the third transverse grooves G3. In the various examples, thecross-sectional shape of the transverse grooves G1 to G4 may be aninverted U-letter shape, an inverted V-letter shape, a trapezoidalshape, or the like.

FIGS. 10 to 12 show Embodiment 7.

In this example, the shoe sole is further provided with a longitudinalgroove GL extending from the first transverse groove G1 to the thirdtransverse groove G3 of FIG. 10. A part of a band 3 is accommodated andplaced in the longitudinal groove GL.

The band 3 of FIG. 11 includes a band portion 30 and anabrasion-resistant material 31 layered together. The abrasion-resistantmaterial 31 is formed by a rubber, for example, and is more resistant toabrasion than the band portion 30. On the other hand, the band portion30 is formed by a non-stretchable tape material. Thus, the band 3 is aband-shaped member that does not substantially stretch even when pulled,but can flex and slack.

The band 3 extends from the fore foot portion F, which is anterior tothe first transverse groove G1, to the rear foot portion R, which isposterior to the third transverse groove G3, and is secured to the shoesole in the fore foot portion F and in the rear foot portion R.

As shown in FIG. 11, the bottom surface of the band 3 is placed abovethe tread surface 1 s. In the fore foot portion F and the rear footportion R, the band 3 is sandwiched between the outsole 1 and themidsole 2, with the lower surface of the band 3 being afloat.

As shown in FIG. 12, the band 3 is tensioned when the toe is elevated orflexed, thereby facilitating the flexion of the middle foot portion Msuch as to raise the arch of the sole as indicated by the solid line.

Next, Text Examples (Sample 1 and Sample 2) and Reference Example (Ref.)will be illustrated in order to elucidate the effects of the presentinvention.

First, Sample 1 having a structure specified in FIGS. 1 to 4, and Sample2 having a structure specified in FIGS. 10 to 12 were produced assamples. On the other hand, an ordinary school shoe with no deeptransverse grooves was provided as a reference example.

Using one male as the subject, angles of deformation of the sole and thefoot portion while running (3.5 min/km) were measured for a plurality ofiterations, and the average values were calculated.

The angle θ along the vertical axis of FIG. 14A represents the angle ofelevation of the first toe. The angle As along the vertical axis of FIG.14B represents the angle of flexion of the sole about the middle footportion. The angle Af along the vertical axis of FIG. 14C represents theangle of flexion of the vertical arch of the foot.

Note that the horizontal axis in FIGS. 14A to 14C represents thepercentage of the length of time from landing until kick-off.

As can be seen from FIG. 14A, the angle θ, i.e., the angle of elevationof the first toe, over the period of heel contact, heel rise and toe offis larger for Sample 1 and Sample 2 than for Reference Example.

As can be seen from FIG. 14B, the angle As, i.e., the angle of flexionof the sole about middle foot portion, over the period of heel contact,heel rise and toe off is larger for Sample 1 and Sample 2 than forReference Example. Particularly, it can be seen that Sample 2, which isprovided with the band, has an even larger value of the angle As thanSample 1.

As can be seen from FIG. 14C, the angle Af, i.e., the angle of flexionof the vertical arch of the foot, at heel contact is smaller for Sample1 and Sample 2 than for Reference Example. However, the angle Af islarger for Sample 1 and Sample 2 than for Reference Example over theperiod of heel rise and toe off. Particularly, it can be seen thatSample 2, which is provided with the band 3, has an even larger value ofthe angle Af than Sample 1.

Thus, it can be expected that shoes of Samples 1 and 2 will realize theeffect of the windlass mechanism, and wearing shoes of Samples 1 and 2will increase or maintain the arch height of the foot.

While preferred embodiments have been described above with reference tothe drawings, various obvious changes and modifications will readilyoccur to those skilled in the art upon reading the presentspecification.

For example, the first transverse groove may be provided only in one ofthe outsole and the midsole.

The band itself may be formed by an abrasion-resistant material such asan aramid fiber. Where the band is provided, the second transversegroove G2 and the third transverse groove G3 may be of the same depth orwidth.

Thus, such changes and modifications are deemed to fall within the scopeof the present invention, which is defined by the appended claims.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a shoe sole of a shoe forwalking, running, training, etc.

REFERENCE SIGNS LIST

1: Outsole, 1 s: Tread surface

2: Midsole

3: Band, 30: Band portion, 31: Abrasion-resistant material

10: Medial edge, 11: Lateral edge

A1: Longitudinal axis

B3: Proximal phalanx, B30: Base

B4: First metatarsal bone, B40: Base, B41: Shaft

BA: Rear foot flexion area, MA: Middle foot flexion area, SA: Auxiliaryflexion area

D1, D2, D3, D4: Average groove width, Da, D20: Width

Bw: Rear wall surface, Fw: Front wall surface, T0: Ceiling

F: Fore foot portion, M: Middle foot portion, R: Rear foot portion

G1: First transverse groove, G2: Second transverse groove, G3: Thirdtransverse groove, G4: Auxiliary transverse groove, GL: Longitudinalgroove

H1, H2, H3, H4: Average depth, Hm: Maximum depth

JS: The Chopart's joint, JL: LISFRANC joint, JLb: Posterior end

NB: Navicular bone, CB: Medial cuneiform bone

MP: Metatarsal phalangeal joint

Ta: Talus, Tb: Posterior end, Tf: Anterior end

T1, T2, T3: Thickness

T2 a, T1 a: Average thickness

X: Transverse direction, Y: Longitudinal direction

1. A shoe sole comprising: an outsole having a tread surface and placedat least in a fore foot portion and a rear foot portion; and a midsoleplaced above the outsole and placed in the fore foot portion, a middlefoot portion and the rear foot portion, wherein: the outsole and/or themidsole define: a first transverse groove continuously extending in atransverse direction from a medial edge so as to reach at least alongitudinal axis of a foot at a position of a metatarsal phalangealjoint and/or a base of a proximal phalanx of first to third toes; atleast one second transverse groove continuously extending in thetransverse direction from the medial edge so as to reach at least thelongitudinal axis, in an area between a Chopart's joint of the first toeto a posterior end of a Lisfranc joint; and at least one thirdtransverse groove continuously extending in the transverse directionfrom the medial edge so as to reach at least the longitudinal axis, inan area between an anterior end to a posterior end of a talus, wherein:the second and third transverse grooves are provided so as to bedepressed upwardly from a bottom surface of the shoe sole; each of thegrooves to has a front wall surface and a rear wall surface opposing thefront wall surface, the front and rear wall surfaces defining each ofthe grooves; an average value of a width of a flexion area is largerthan an average groove width of the first transverse groove and islarger than an average groove width of each of the at least one secondtransverse groove, wherein the flexion area is an area extending from amost anterior one of the front wall surfaces of the at least one thirdtransverse groove to a most posterior one of the rear wall surfaces ofthe at least one third transverse groove; and an average depth of the atleast one second transverse groove is larger than an average depth ofthe first transverse groove and is equal to or larger than an averagedepth of each of the at least one third transverse groove.
 2. The shoesole according to claim 1, wherein an average groove width of at leastone of the third transverse groove is larger than the average groovewidth of the first transverse groove and is larger than the averagegroove width of each of the at least one second transverse groove. 3.The shoe sole according to claim 2, further comprising an auxiliarytransverse groove continuously extending in the transverse directionfrom the medial edge so as to reach at least the longitudinal axis at aposition directly below a base or a shaft of a first metatarsal bone. 4.The shoe sole according to claim 3, wherein an average depth of theauxiliary transverse groove is smaller than the average depth of thesecond transverse groove, and an average groove width of the auxiliarytransverse groove is smaller than the average groove width of at leastone of the third transverse groove.
 5. The shoe sole according to claim1, wherein the first transverse groove is depressed upwardly from thetread surface.
 6. The shoe sole according to claim 5, wherein: each ofthe grooves is defined by a front wall surface, a rear wall surface anda ceiling above; a thickness from an upper surface of the midsole to theceiling of the first transverse groove is set to be 0.5 mm or more andless than 12 mm at a thinnest portion; a thickness from the uppersurface of the midsole to the ceiling of the second transverse groove isset to be 0.5 mm or more and 10 mm or less at a thinnest portion; and athickness from the upper surface of the midsole to the ceiling of thethird transverse groove is set to be 0.5 mm or more and 10 mm or less ata thinnest portion.
 7. The shoe sole according to claim 1, wherein: amaximum depth of the second and third transverse grooves is 5 mm or moreand 40 mm or less; the maximum depth of each of the at least one secondtransverse groove is larger than a thickness of a portion of the midsolethat is directly above an area where the second transverse groove havingthat maximum depth is provided; and the maximum depth of each of the atleast one third transverse groove is larger than a thickness of aportion of the midsole that is directly above an area where the thirdtransverse groove having that maximum depth is provided.
 8. The shoesole according to claim 1, wherein: the average depths of the second andthird transverse grooves are 5 mm or more and 40 mm or less; the averagedepth of at least one of the second transverse groove is larger than anaverage thickness a of a portion of the midsole that is directly abovean area where the at least one second transverse groove is provided; andthe average depth of at least one of the third transverse groove islarger than an average thickness a of a portion of the midsole that isdirectly above an area where the at least one third transverse groove isprovided.
 9. The shoe sole according to claim 1, wherein: the secondtransverse groove continuously extends across the shoe sole from themedial edge to a lateral edge of the foot; and the second transversegroove has a larger average depth on a medial side of the foot than anaverage depth of the second transverse groove on a lateral side of thefoot.
 10. The shoe sole according to claim 1, wherein: the thirdtransverse groove continuously extends across the shoe sole from themedial edge to a lateral edge of the foot; and the third transversegroove has a larger average depth on a medial side of the foot than anaverage depth of the third transverse groove on a lateral side of thefoot.
 11. The shoe sole according to claim 1, wherein the at least onesecond groove comprises a plurality of second transverse grooves, andthe average depth of at least two second transverse grooves is largerthan the average depth of the first transverse groove and is equal to orlarger than the average depth of each of the at least one thirdtransverse groove.
 12. The shoe sole according to claim 2, wherein theat least one third transverse groove comprises a plurality of thirdtransverse grooves, and an average groove width of at least two of thethird transverse grooves is larger than the average groove width of thefirst transverse groove and is larger than the average groove width ofeach of the at least one second transverse groove.
 13. The shoe soleaccording to claim 1, wherein: the shoe sole is further provided with alongitudinal groove extending from the first transverse groove to thethird transverse groove; and the shoe sole further comprises a bandportion placed in the longitudinal groove, the band portion extendingfrom the fore foot portion, which is anterior to the first transversegroove, to the rear foot portion, which is posterior to the thirdtransverse groove, the band portion being secured to the shoe sole inthe fore foot portion and in the rear foot portion, and the band portionbeing formed by a material that is less stretchable than the midsole andthe outsole
 14. The shoe sole according to claim 13, wherein anabrasion-resistant material 34, which is less susceptible to abrasionthan the band portion, is attached to a lower surface of the bandportion, and the band portion and the abrasion-resistant materialtogether form a band.
 15. The shoe sole according to claim 14, wherein abottom surface of the band is placed above the tread surface.